Abram bought a cave and surrounding area to bury Sarah

 Genesis 23:1-20

Sarah lived to be a hundred and twenty-seven years old. She died at Kiriath Arba (that is, Hebron) in the land of Canaan, and Abraham went to mourn for Sarah and to weep over her.

Then Abraham rose and bowed down before the people of the land, the Hittites. He said to them, “If you are willing to let me bury my dead, then listen to me and intercede with Ephron son of Zohar on my behalf so he will sell me the cave of Machpelah, which belongs to him and is at the end of his field. Ask him to sell it to me for the full price as a burial site among you.”

Again Abraham bowed down before the people of the land and he said to Ephron in their hearing, “Listen to me, if you will. I will pay the price of the field. Accept it from me so I can bury my dead there.”  Ephron answered Abraham, “Listen to me, my lord; the land is worth four hundred shekels of silver, but what is that between you and me? Bury your dead.”

Abraham agreed to Ephron’s terms and weighed out for him the price he had named in the hearing of the Hittites: four hundred shekels of silver, according to the weight current among the merchants.

Afterward Abraham buried his wife Sarah in the cave in the field of Machpelah near Mamre (which is at Hebron) in the land of Canaan. So the field and the cave in it were deeded to Abraham by the Hittites as a burial site.

Abraham hoped his wife could be buried in the Hittites, so he refused to borrow the land so he purchased the cave and land to be his in the Canaan area.

How?
Until now, Abram did not know where the promised land but he insisted on purchasing a land there for Sarah, which is the first step to God's promise to him and his people.